move backend to subfolder

tanks-backend/DisplayCommands/Internals/DisplayCommand.cs

@@ -0,0 +1,17 @@
+namespace DisplayCommands.Internals;
+
+internal enum DisplayCommand : ushort
+{
+    Clear = 0x0002,
+    Cp437Data = 0x0003,
+    CharBrightness = 0x0005,
+    Brightness = 0x0007,
+    HardReset = 0x000b,
+    FadeOut = 0x000d,
+    [Obsolete("ignored by display code")] BitmapLegacy = 0x0010,
+    BitmapLinear = 0x0012,
+    BitmapLinearWin = 0x0013,
+    BitmapLinearAnd = 0x0014,
+    BitmapLinearOr = 0x0015,
+    BitmapLinearXor = 0x0016
+}

tanks-backend/DisplayCommands/Internals/DisplayConnection.cs

@@ -0,0 +1,126 @@
+using System.Buffers;
+using System.Diagnostics;
+using System.Net;
+using System.Net.Sockets;
+using System.Runtime.InteropServices;
+using Microsoft.Extensions.Options;
+
+namespace DisplayCommands.Internals;
+
+internal sealed class DisplayConnection(IOptions<DisplayConfiguration> options) : IDisplayConnection, IDisposable
+{
+    private readonly ArrayPool<byte> _arrayPool = ArrayPool<byte>.Shared;
+    private readonly UdpClient _udpClient = new(options.Value.Hostname, options.Value.Port);
+
+    public ValueTask SendClearAsync()
+    {
+        var header = new HeaderWindow { Command = (ushort)DisplayCommand.Clear };
+
+        return SendAsync(header, Memory<byte>.Empty);
+    }
+
+    public ValueTask SendCp437DataAsync(ushort x, ushort y, Cp437Grid grid)
+    {
+        var header = new HeaderWindow
+        {
+            Command = (ushort)DisplayCommand.Cp437Data,
+            Height = grid.Height,
+            Width = grid.Width,
+            PosX = x,
+            PosY = y
+        };
+
+        return SendAsync(header, grid.Data);
+    }
+
+    public ValueTask SendCharBrightnessAsync(ushort x, ushort y, ByteGrid luma)
+    {
+        var header = new HeaderWindow
+        {
+            Command = (ushort)DisplayCommand.CharBrightness,
+            PosX = x,
+            PosY = y,
+            Height = luma.Height,
+            Width = luma.Width
+        };
+
+        return SendAsync(header, luma.Data);
+    }
+
+    public async ValueTask SendBrightnessAsync(byte brightness)
+    {
+        var header = new HeaderWindow { Command = (ushort)DisplayCommand.Brightness };
+
+        var payloadBuffer = _arrayPool.Rent(1);
+        var payload = payloadBuffer.AsMemory(0, 1);
+        payload.Span[0] = brightness;
+
+        await SendAsync(header, payload);
+        _arrayPool.Return(payloadBuffer);
+    }
+
+    public ValueTask SendHardResetAsync()
+    {
+        var header = new HeaderWindow { Command = (ushort)DisplayCommand.HardReset };
+        return SendAsync(header, Memory<byte>.Empty);
+    }
+
+    public async ValueTask SendFadeOutAsync(byte loops)
+    {
+        var header = new HeaderWindow { Command = (ushort)DisplayCommand.FadeOut };
+
+        var payloadBuffer = _arrayPool.Rent(1);
+        var payload = payloadBuffer.AsMemory(0, 1);
+        payload.Span[0] = loops;
+
+        await SendAsync(header, payload);
+        _arrayPool.Return(payloadBuffer);
+    }
+
+    public ValueTask SendBitmapLinearWindowAsync(ushort x, ushort y, PixelGrid pixels)
+    {
+        var header = new HeaderWindow
+        {
+            Command = (ushort)DisplayCommand.BitmapLinearWin,
+            PosX = x,
+            PosY = y,
+            Width = (ushort)(pixels.Width / 8),
+            Height = pixels.Height
+        };
+
+        return SendAsync(header, pixels.Data);
+    }
+
+    public string GetLocalIPv4()
+    {
+        using var socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 0);
+        socket.Connect(options.Value.Hostname, options.Value.Port);
+        var endPoint = socket.LocalEndPoint as IPEndPoint ?? throw new NotSupportedException();
+        return endPoint.Address.ToString();
+    }
+
+    private async ValueTask SendAsync(HeaderWindow header, Memory<byte> payload)
+    {
+        int headerSize;
+        unsafe
+        {
+            // because we specified the struct layout, no platform-specific padding will be added and this is be safe.
+            headerSize = sizeof(HeaderWindow);
+        }
+
+        Debug.Assert(headerSize == 10);
+        var messageSize = headerSize + payload.Length;
+
+        var buffer = _arrayPool.Rent(messageSize);
+        var message = buffer.AsMemory(0, messageSize);
+
+        MemoryMarshal.Write(message.Span, header);
+        payload.CopyTo(message[headerSize..]);
+
+        await _udpClient.SendAsync(message);
+
+        _arrayPool.Return(buffer);
+    }
+
+    public void Dispose() => _udpClient.Dispose();
+}

tanks-backend/DisplayCommands/Internals/DisplaySubCommand.cs

@@ -0,0 +1,10 @@
+namespace DisplayCommands.Internals;
+
+internal enum DisplaySubCommand : ushort
+{
+    BitmapNormal = 0x0,
+    BitmapCompressZ = 0x677a,
+    BitmapCompressBz = 0x627a,
+    BitmapCompressLz = 0x6c7a,
+    BitmapCompressZs = 0x7a73
+}

tanks-backend/DisplayCommands/Internals/HeaderBitmap.cs

@@ -0,0 +1,19 @@
+using System.Runtime.InteropServices;
+using EndiannessSourceGenerator;
+
+namespace DisplayCommands.Internals;
+
+[StructEndianness(IsLittleEndian = false)]
+[StructLayout(LayoutKind.Sequential, Pack = 16, Size = 10)]
+internal partial struct HeaderBitmap
+{
+    private ushort _command;
+
+    private ushort _offset;
+
+    private ushort _length;
+
+    private ushort _subCommand;
+
+    private ushort _reserved;
+}

tanks-backend/DisplayCommands/Internals/HeaderWindow.cs

@@ -0,0 +1,19 @@
+using System.Runtime.InteropServices;
+using EndiannessSourceGenerator;
+
+namespace DisplayCommands.Internals;
+
+[StructEndianness(IsLittleEndian = false)]
+[StructLayout(LayoutKind.Sequential, Pack = 16, Size = 10)]
+internal partial struct HeaderWindow
+{
+    private ushort _command;
+
+    private ushort _posX;
+
+    private ushort _posY;
+
+    private ushort _width;
+
+    private ushort _height;
+}